Non-Rayleigh scattering by a randomly oriented elongated scatterer

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Abstract

The echo statistics of a randomly rough, randomly oriented prolate spheroid that
is randomly located in a beampattern are investigated from physics-based principles
both analytically and by Monte Carlo methods. This is a direct-path geometry in
which reflections from neighboring boundaries are not a factor. The center of the
prolate spheroid is assumed to be con fined to the plane containing the MRA (maximum
response axis). Additionally, the rotation of the prolate spheroid is assumed
to always be in this plane. The statistics and, in particular, the tails of the probability
density function (PDF) and probability of false alarm (PFA) are shown to
be strongly non-Rayleigh and a strong function of shape of scatterer. The tails are
shown to increase above that associated with a Rayleigh distribution with increasing
degree of elongation (aspect ratio) of the scatterer and when roughness effects are introduced. And, as also shown in previous studies, the effects associated with
the scatterer being randomly located in the beam contribute to the non-Rayleigh
nature of the echo. The analytically obtained results are compared to Monte Carlo
simulations for verification.

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Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution August 2012

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